Current transmission networks are mainly based on the Synchronous Digital Hierarchy abbreviated as SDH, see ITU-T G.707, 12/2003. A new hierarchy, the Optical Transport Hierarchy abbreviated as OTH has been standardized in ITU-T G.709 03/2003, which is incorporated by reference herein. The purpose of OTH is to deal more economically with very large bandwidths, which are termed Optical Channel Data Units and abbreviated as ODUs. Currently defined are ODU1 (˜2.7 Gbit/s), ODU2 (˜10.7 Gbit/s), and ODU3 (˜43 Gbit/s). New efficient overlay networks can be defined, build and used by network operators based on this hierarchy. The architecture of optical transport networks is described in ITU-T G.872 (11/2001), which is also incorporated by reference herein.
As Ethernet is more and more upcoming as the primary transport format for data signals, 1 Gbit/s Ethernet signals would be a natural client signal for the business of OTH network operators.
The currently standardized method to transport a 1 Gbit/s Ethernet signal through an Optical Transport Network includes to map the 1 Gbit/s Ethernet signal into a concatenation of SDH Virtual Containers (SDH VCs) and than to map the framed SDH transport signal into an ODU. This can be seen for instance from ITU-T G7041 (12/2003) on page 47. The existing mapping of 1 Gbit/s signals into SDH Virtual Containers (SDH VCs) is, however, expensive as it requires to operate a functionally independent SDH network. This in many cases would not be necessary for backbone network operators only dealing with large capacities.
On the other hand, a mapping of a single 1 Gbit/s Ethernet into the smallest OTH entity (˜2.7 Gbit/s) would, however, encompass an enormous waste of bandwidth.
As 1 Gbit/s Ethernet signals are currently gaining much importance as a main client signal to be transported in long-haul networks, there exists a need to ensure a cost effective transport of these signals.
It is therefore an object of the present invention to provide a method and related network element, which allows a more efficient transport of client signals over an optical transport network and which is particularly suited for the transport of 1 Gbit/s Ethernet signals.